Surfboards typically have either one large fin or three small fins. In the case of a single fin surfboard, the fin is usually fixed on the underside of the board towards its tail along the centre line. A three-fin surfboard usually includes a fin attached to the underside of the rear of the board on its centre line, and the other two side fins placed symmetrically towards the outside edges of the board. The two side fins are usually raked outwards by around 4 degrees compared to the centre fin.
Surfboard fins are either permanently fixed to a surfboard by means of fibreglass resin, or are removable, using a variety of fixing systems.
Fixed fins are generally stronger and stiffer than removable fins and are expected is to give better performance when surfing. Fixed fins are more expensive to install and replace if damaged. They are also more cumbersome to transport.
By contrast, removable fins are secured to a surfboard, generally via a fin box, which is typically permanently fixed to the surfboard by a polyester resin. Prior art removable fins have an inferior performance compared to fixed fins due to the less rigid mounting. However, removable fins are advantageous in that 1) they allow a surfer to choose a specific type of fin to suit his or her own style of surfing; 2) fins can be changed for different conditions and may easily be replaced if broken; and 3) the surfboard itself is less susceptible to damage than the fin. As such, when the fin breaks, it is not uncommon that the surfboard remains intact. Some fins in the marketplace such as those disclosed in U.S. Pat. No. 7,025,645 and U.S. Pat. No. 5,567,190 can be replaced and adjusted to suit different conditions for better performance but this requires complex re-positioning of the fin.
One of the main deficiencies of removable fins is the susceptibility of the fin box to flexing in the surfboard. This means that the fin is likely to move with the flexing box, thereby impairing the performance of the fin. To address this problem, some fin boxes in the marketplace are secured to the hard top face of the surfboard either by means of a screw fixing or an adhesive fixing to the inside face of the top surface.
The total weight of a surfboard is also critical. A surfboard should preferably be kept as light as possible. Generally speaking, the lighter the box and less resin used for installation in the board, the better the surfboard performs.
The ease of installation of the fin box into the surfboard is of critical importance to a fin system. If the fin box is too difficult or takes too long to install, it will not be welcomed by surfboard shapers. Ease and speed of installation are therefore believed to have a huge influence on the sale of surfboard fin systems.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of each claim of this application.